The role of cavitation as a mechanism of damage associated with diagnostic and therapeutic ultrasound, and the phenomena of ultrasonically induced cavitation in mammalian tissues are investigated. Studies include (1) identification of the anatomical sites of onset of cavitation in mammalian systems, (2) determination of levels at which cavitation is involved in effects on mammalian systems for continuous wave exposures at clinical frequencies, (3) determination of levels at which cavitation is involved in effects on mammalian systems for repetitive pulse exposures at clinical frequencies, and (4) determination of the role of "steady cavitation" and/or "transient cavitation" phenomena to the safe clinical application of therapeutic and diagnostic ultrasound. The study utilizes structural and functional endopoints and contributes to the understanding of the physical mechanisms of interaction of ultrasound and biological media.